The present positioning collar invention is particularly suitable for use in, for example, a high tension cable stringing apparatus such as that described in U.S. Pat. No. 4,339,212. In operation, clamping devices may be placed in abutting relationship to the cable reel of such an apparatus for the purpose of preventing the cable reel from sliding axially on the shaft in an undesirable manner.
In high tension wire stringing, wire discharged from a cable reel, at a desired and controlled rate, is strung across utility poles. During stringing, if any axial movement of the cable reel occurs it can cause horizontal flapping of the high tension wire as it is being discharged from the cable reel. Flapping of the wire being put up can result in contact with existing wire and even breakage thereof, possibly causing great harm to persons and property.
It has thus been an objective of the art to devise clamping devices that will eliminate this axial movement of the cable reel and the resultant wire flapping while, in addition, enabling easy loading and unloading of the cable reel or spool when the wire thereon has been expired. The commonly known clamping devices heretofore utilized have been collar-like structures provided with arrangements of a plurality of set screws that permit adjustable fixing with respect to the axle. There are numerous disadvantages and shortcomings which have been encountered with the set-screw devices. For example, the set screws may get separated from the clamping body or, because they have to be tightened and loosened with a wrench, corroded or damaged threads may impair the ability to secure or release the set screws. Moreover, because each of the plurality of set screws must be tightened and loosened, changing the cable reels during operation is slow and tedious and generally undesirable. Similar problems have been encountered with split collar clamping devices utilizing nuts and bolts to clamp them to the shaft.
A solution of these problems was presented by the clamping device of my prior application Ser. No. 939,243, filed 9/5/78 now abandoned, in that it was easily mounted on, removed from and positioned on an axle supporting a cable reel, as well as being fairly inexpensive to manufacture and devoid of separable parts. This was achieved by an annular collar having a central longitudinal opening adapted to receive an axle or shaft and an intersecting transverse opening which received a shiftable, captively mounted lock pin. The lock pin had a tapered surface portion which when moved in one direction affected an interference fit with the shaft and when moved in the opposite direction formed a clearance allowing the collar to be moved easily along the shaft. Other similar devices are found to have been disclosed in German Pat. No. 671,920; U.S. Pat. Nos. 1,408,993; 2,627,431; 302,519; 291,728; 1,458,802, 2,785,814; and Swedish Pat. No. 124,927, all cited in the file of my abandoned application Ser. No. 939,243.
However, problems arose in connection with proper use and safety aspects of the wedge locking type collars. Personnel in the field applying hammers and the like to pound the lock pin in one direction or the other would lose sight of the proper side to strike for unlocking, and excessive striking in the wrong direction led to flaring or chipping of the lock pin and even in the sending off of flying pieces. Excessive wedging beyond that necessary brought about similar actions to then drive the pin in the opposite direction for unlocking. Therefore, I developed an improved clamping collar wherein the locking pin has provision for eliminating the flairing and chipping of ends by severe hammer blows (Sauber U.S. Pat. No. 4,339,212). Despite the features of this collar, however, there could still be possible dangers occasioned by swinging a hammer to drive and loosen the locking pin, and excessive wedging of the locking pin beyond that necessary might still occur. More importantly, however, workers find discomfort and fatigue in holding and carrying the heavy hammers used for operating clamping collars requiring striking action to tighten and loosen.